Sharif Digital Repository

In this article, a new variational approach for extraction of leaky modes in layered waveguides is proposed. To verify the method, results of analysis of a typical test case is compared to the other references, being in agreement with them. The efficiency of the proposed approach is compared to other reported methods  

In this article, a new variational approach for extraction of guided and leaky modes in layered waveguides is proposed. To verify the method, results of analysis of a typical test case is compared to the other references, being in agreement with them. The efficiency of the proposed approach is compared to other reported methods  

In this paper the fabrication, testing and results of inverse profiling of optical slab waveguides in glass are reported. This is the first successful report of fabricating ion exchange optical waveguides in Iran. © Shiraz University  

Excitation and propagation of the surface polaritonic rogue waves and breathers are investigated by proposing a coupler free optical waveguide that consists of a transparent layer, middle negative index metamaterial layer, and bottom layer of the cold four level atomic medium. In this planar optical waveguide, a giant controllable Kerr nonlinearity is achieved by sufficient field concentration and a proper set of intensities and detunings of the driven laser fields. As a result, various kinds of temporal surface polaritonic solitons, rogue waves, and breathers can be propagated in the narrow window for electromagnetically induced transparency. We find that the giant intensity and extreme... 

In this paper, we study the backaction effect on the force exerted upon Rayleigh particles in guided structures. We show that the backaction becomes stronger as the group velocity of the guided modes is decreased, which is not unexpected since the fall of group velocity increases the interaction time between the particle and the electromagnetic field. Interestingly, the sign of the group velocity affects the pushing and pulling nature of the exerted electromagnetic force. We specifically investigate the case of a single mode optical waveguide both in the propagating and evanescent regimes, and show that the backaction enables us to enhance the ratio of the potential depth to the trapping... 

In this paper a simulation of the transverse localization of light in 1D array of optical waveguides in the presence of off-diagonal disorder is presented. Effects of self-focusing and self-defocusing Kerr nonlinearity on the transverse localization of surface and bulk modes of the disordered waveguides array are taken into consideration. The simulation shows that in the off-diagonal disordered array at low nonlinear parameters, the transverse localization of light becomes more than that of the corresponding diagonal disordered array. However by increasing the nonlinear parameters the diagonal disordered array is localized more than the associated off-diagonal disordered array for both... 

In this paper, the effects of the long-range correlated diagonal disordered optical waveguide arrays in the presence and absence of the positive Kerr nonlinearity are analyzed numerically. The calculated inverse localization length shows that the long-range correlation in a disordered system causes a decrease in the transverse localization in linear optical waveguide arrays. In the presence of positive Kerr nonlinearity, the inverse localization length is increased by increasing the nonlinear parameters in long-range correlated disordered systems in comparison with the uniform distribution disordered systems. This means that the long range correlation causes an enhancement of transverse... 

A novel method for computation of guided mode reflectivity from optical waveguide end-facet is presented. The method is based on the characteristic Green's function (CGF) technique formulation combined with the complex images (CIs) method for dielectric planar waveguides. By separability assumption of the structure, a uniform and closed-form expression of spatial Green's function is obtained. Derived expression consists of discrete and continuous spectrum contributions which denote guided and radiation modes effects, respectively. Having a full-wave solution, efficient optimization procedure is then used to calculate the exact reflection coefficients of guided modes at the end-facets. To... 

The high degree of intensity values in microring resonators needs a careful treatment of nonlinear phenomena. Nonlinear effects are analyzed in coupling problem of ring-ring directional couplers. It has been observed that the nonlinearity affects the coupling device dramatically, and can be used as controlling techniques in such as coupled resonator optical waveguides. © 2007 Elsevier B.V. All rights reserved  

Based on the mathematical similarity of the Schrödinger and Helmholtz equations, the tight-binding method has been employed for solving optical waveguide problems, in a manner similar to the methods commonly used in solid-state physics. The solutions (TE mode electric field waveforms and propagation constants) of a single dielectric slab waveguide are considered to be known, and tight-binding is used to compute the propagation constants of several multi-waveguide structures. Analytical solutions are derived for linear and circular arrays of adjacent waveguides. The problem of two similar adjacent waveguides is treated in detail for two cases of similar and different propagation constants of... 

We present a new method for modeling and design of photonic crystal nano-beam resonators (PCNBRs) based on cascaded transmission lines. The proposed model provides an accurate estimate of the PCNBRs properties such as resonance wavelength and quality factor (Q) with much smaller computation cost as compared to the brute-force numerical methods. Furthermore, we have developed a straightforward technique for the design of high-Q PCNBRs based on resonance modes with Gaussian electromagnetic field profiles. The results obtained by using the proposed transmission line model are compared against numerical and experimental results and the accuracy of the model is verified. The proposed model... 

We propose an exactly solvable waveguide lattice incorporating an inhomogeneous coupling coefficient. This structure provides classical analogs to the squeezed number and squeezed coherent intensity distribution in quantum optics where the propagation length plays the role of a squeezed amplitude. The intensity pattern is obtained in a closed form for an arbitrary distribution of the initial beam profile. We have also investigated the phase transition to the spatial Bloch-like oscillations by adding a linear gradient to the propagation constant of each waveguide (α). Our analytical results show that the Bloch-like oscillations appear above a critical value for the linear gradient of the... 

The possibility of electromagnetic slow wave propagation in dielectric slab waveguides, when free two-dimensional interface charge layers are generated at film-substrate and film-cover interfaces, is already explored. In this paper, the propagation of electromagnetic slow waves supported by induced charge layers of nonzero thickness, whose induced charge densities have Gaussian profiles, is investigated for the first time. In order to analyze the effects of inhomogeneity in the conductivity profile, the electric field is expanded in terms of Hermite polynomials and each eigenmode is sought in the complete space spanned by them. © 2007 IEEE  

Analytical analysis of straight single-line defect optical waveguides in two dimensional photonic crystals based on expanding electromagnetic fields in terms of Hermite polynomials is reported. This novel electromagnetic field expression is substituted in Helmholtz equation, a new set of linear ordinary differential equations with variable coefficients are obtained, and by employing differential transfer matrix method; defect modes, i.e. the guided modes propagating in the line defect waveguide, are analytically derived. The validity of the results obtained by applying the proposed approach are confirmed by comparing them to those derived by using finite difference time domain method  

A novel method for computation of modal reflectivity at optical waveguide end-facet is presented. The method is based on the characteristic Green's function (CGF) technique. Using separability assumption of the structure and rational function fitting method (RFFM), a closed-form field expression is derived for optical planar waveguide. The uniform derived expression consists of discrete and continuous spectrum contributions which denotes guided and radiation modes effects respectively. An optimization problem is then defined to calculate the exact reflection coefficients at the end-facet for all extracted poles obtained from rational function fitting step. The proposed CGF-RFFM-optimization... 

In this article, a novel approach based on differential transfer matrix method is proposed for fast analysis and optimization of wideband planar tapered directional couplers. In this method, both even and odd modes can be analyzed independently to obtain overall scattering matrix. The new method accelerates the optimization time considerably in planar structures. An 8.34 dB tapered coupler in the frequency band of 1-12 GHz is designed and optimized in the form of offset stripline structure. The experimental result shows good agreement with theory